1. Time travel

You start in the corner of the Wishing Tree field, where a smoking farmstead called the Swamp Shack hosts country and bluegrass bands on its decrepit porch. Ignoring the dubstep and disco DJs cranking out riot mashes inside, we're deep in the American south, sometime around the turn of the 20th century. A couple of hundred yards in-site finds us in 30s England at the Knees Up tent, where performers dressed as seaside postcard caricatures lead us through music hall singalongs played on an instrument we believe is officially called "the Joanna", and written in times when manners were valued above money and no meal was more celebrated in song/bunny ear mime than a hearty dish of rabbit.

Then five minutes across the Bollywood field and you're in bohemian 50s LA amid the cabaret stylings of the Black Dahlia tent. Truly, Bestival is like a totally trolleyed Tardis.

2. Almost die, in a controlled environment

As something of a side-hugger when it comes to rollerskating, it was foolhardy indeed to swap the security of a sturdy Wellington for two four-wheeled disco death-traps and venture into the Rollerdisco tent. Yet, a couple of wobbly minutes in, I'm holding my own in the clockwise cycle, my rhythm aided by the calf-gliding 70s beats. Then, the MC tries to commit the perfect murder. "Now… THE OPPOSITE WAY!" he yells, and for a man who can just as much turn around on rollerskates as he can rewire the Large Hadron Collider, it causes a limb-shattering pile-up akin to 2 Fast 2 Furious with more bubble wigs.

3. Get motivated

After a relaxing Sunday afternoon game of crazy golf, chilling to reggae in a pagoda on a hidden lake near the Troll Kissing Chair in the Ambient Forest (man, yesterday's corn chowder soup was strong stuff) and the intense strain of trying to hear any of Noah and The Whale from as near as we can get to the Big Top tent, we need a low-key disco workdown. So it's back to the Rollerdisco tent where Mr Motivator, in a leotard so loud they can probably hear it in Portsmouth, is leading a tent-bursting crowd in minor leg-bending, grunting and arm-raising exercises we suspect might have been developed for the over-80s. "Give me more horse!" he exclaims at one point, which turns out to be the name of one of the exercise moves, and not some deep-rooted drug problem rearing its head at the most inopportune moment.

4. Decide the future of music

With Kelis providing mash-ups of Nirvana, Madonna and Milkshake on the main stage, it's in every music hack's DNA to shun such crass behaviour and head to the Big Top to decide which of Bestival's premier Critic's Acts is actually going to change the world: James Blake or Zola Jesus? Blake weighs in with some subtle early jabs, his bliptronic xx moods melding student soul, vocoder dubstep and familial dislocation – on I Never Learnt to Share at least – to create a very human machine music. There's comedy in the fact that his drummer has a bass drum pad the size of a festival pizza and at the point when, four songs in, Blake seems to hit a Smurf vocal pedal by accident. But his click-track Anthony Hegarty fuzz-step is entrancing, and might well be the sound of Radio 2 in 2034. Or possibly the death of dubstep that Andrew Maxwell was calling for in the comedy tent yesterday.

Zola Jesus certainly loses on crowd pull – she's up against Björk, after all – but wins on showmanship, looking like Björk's swan dress come to life and stomping around the stage like a feral Stevie Nicks. Her gothtronic impression of Florence and the Seriously Heavy Machinery has legs too, akin to what Let England Shake might have sounded like if Siouxsie Sioux had made it. Once the phrase "Bonnie Tyler" enters your head though, it's all over. Blake wins, with several knockouts.

5. Turn Biophiliac

"With Biophilia comes a restless curiosity, an urge to investigate and discover the elusive places where we meet nature," intones David Attenborough in voiceover, "where she plays on our senses with colours and forms, perfumes and smells…" As a mass of spangly choristers gather on a stage bedecked with luminous xylophones and as hi-def images of viruses, DNA, moons and tesseracts fill the screens, the remaining Bestival faithful start wondering why no one's offered them any of this Biophilia shit all weekend and whether their mate Steve can score any at the Psychedelic Worm.

Once Björk skips on to the sparse, freeform avant-shinto of Thunderbolt – the prevailing style of the new album determines much of the set — it's clear there are more complex issues to be considered about the relationship between nature (represented by the choir), technology (the "band" and their instruments) and music, ie Björk herself, with a shock of ginger afro, pencil skirt and aquamarine jacket and shark's fin hat; dressed, perhaps, as a metaphor for a technology-throttled planet but looking for all the world like an Oompa-Loompa air stewardess on Virgin Galactic.

What we learn from Björk's set, though, is that an obsession with technology tends to muffle music. Where the album was an exercise in boundless invention – interconnected pendulums playing the sound of the earth, Tesla coils adapted as instruments – on a festival stage it's too flat and exclusive an experience. Despite creative use of the choir, some nifty handheld fireworks and the frenetic melody of Crystalline, Björk's show is exactly what you'd expect from watching an app onstage: cold, colourful and baffling to the mildly sozzled. Björk slapping an iPad connected to a pipe organ seems more gimmick than genius, and often the tech is so minimalist she seems to be dancing to non-existent beats.

It's when the human element bursts through that the set starts to sparkle. The palpable terror in the crowd when a Chinese lantern is blown directly on to the stage. The churchy disquiet of Hollow and the moments when the choir lets rip stirring crescendos of Bond-style elation. Or when, sticking to her minimalist Biophiliac guns, she throws in a light smatter of actual hits – a stark but moving One Day accompanied only by an alien/African instrument we shall call the Coneophone, a shiver-inducing Hooligans of the Night and a final, rousing stampede through Declare Independence.

You expect spectacle from Björk, but this was more oddity. With the Ambient Forest full of acid fractals projected on to lakes and the Bestival closing parade featuring fireworks, ticker tape, a cloud of luminous balloons and 12ft bubble-headed ghosts swaying in circles on stilts, Bestival itself has out-Björked Björk.